Useful R code 2

 

Date: 2021-08-10
R version: 3.5.0
*Corresponding author: matthew.malishev@gmail.com
This document can be found at https://github.com/darwinanddavis/UsefulCode

Overview

Same deal as Useful Code, but the second instalment because the first one has too much stuff in it and now runs slow.

Colour palettes

Colorspace

require(colorspace)
hcl_palettes(plot = TRUE)  # show all palettes

# https://cran.r-project.org/web/packages/colorspace/vignettes/colorspace.html
require(colorspace)
q4 <- qualitative_hcl(4, palette = "Dark 3")  # discrete
s9 <- sequential_hcl(9, "Purples 3")  # continuous
# for ggplot
scale_color_discrete_sequential(palette = "Purples 3", nmax = 6, order = 2:6)
# for colospace functions: hcl_palettes() %>% str hcl_palettes()['type']

Neon colour palettes

# https://www.shutterstock.com/blog/neon-color-palettes
neon1 <- c("#3B27BA", "#FF61BE", "#13CA91", "#FF9472")
neon2 <- c("#FFDEF3", "#FF61BE", "#3B55CE", "#35212A")
neon3 <- c("#FEA0FE", "#F85125", "#02B8A2", "#535EEB")
neon4 <- c("#535EEB", "#001437", "#C6BDEA", "#FFAA01")
scales::show_col(c(neon1, neon2, neon3, neon4))

Hexadecimal color code for transparency
See https://gist.github.com/lopspower/03fb1cc0ac9f32ef38f4.

require(colorspace)
require(stringr)
colv <- c("#004616", sequential_hcl(5, "Lajolla"))
str_sub(colv, 0, 1) <- "#66"  # add alpha opac to col vector

D3

Links
-
-
-

D3 and leaflet

# devtools::install_github('jcheng5/d3scatter')
require(pacman)
p_load(d3scatter, crosstalk, leaflet, tibble, httpuv)

sd <- SharedData$new(quakes[sample(nrow(quakes), 100), ])
# sd$data() %>% head

bscols(widths = c(12, 6, 6), filter_slider("stations", "Stations", sd, ~stations), leaflet(sd, width = "100%", 
    height = 400) %>% addTiles() %>% addCircleMarkers(lng = sd$data()[, "long"], lat = sd$data()[, "lat"], 
    stroke = F, fill = T, color = "red", fillOpacity = 0.5, radius = ~mag + 2, label = ~paste0("Depth: ", 
        as.character(depth))), d3scatter(sd, width = "100%", height = 400, ~mag, ~depth, color = ~stations))

Stations

Convert R code to D3 https://rstudio.github.io/r2d3/articles/visualization_options.html

Create calendar plot

# https://rstudio.github.io/r2d3/articles/gallery/calendar/ install.packages('r2d3')
require(r2d3)
require(readr)
require(dplyr)
require(colorspace)
require(scales)
require(stringr)

# col pal
col <- "PuBuGn"  # seq
col2 <- "Tropic"  # diverge

# seq
pal <- sequential_hcl(12, col)
# pal %>% show_col(borders = NA,labels=F)
paste0("\"", pal, "\"") %>% cat(sep = ",")

"#004533","#005C4E","#00726F","#008795","#0095B5","#56A0C8","#8FACD6","#B6BAE0","#D2CAE7","#E6DAEE","#F5EAF5","#FFF7FD"

# diverge
pal <- diverge_hcl(12, col2)
# pal %>% show_col(borders = NA,labels=F) paste0(''',pal,''') %>% cat(sep=',')

cal <- read_csv("https://raw.githubusercontent.com/rstudio/r2d3/master/vignettes/gallery/calendar/dji-latest.csv")

r2d3(data = cal, d3_version = 4, container = "div", options = list(start = 2006, end = 2011), script = "calendar.js")

Data frames

Reversing order of rows in dataframe

# df = data.frame
require(tidyverse)
df %>% map_df(rev)

Visualise data structure as tree

# explore package
require(DataExplorer)
require(palmerpenguins)
p <- penguins
plot_str(p)

dplyr basics

require(dplyr,gapminder)
pacman::p_load(gapminder)

# mutate
africa_ranked <- mutate(gapminder, 
       "African" = continent == "Africa",
       "RankPop" = rank(desc(pop))
       ) 

africa_ranked %>% glimpse() # visualise the data
africa_ranked %>% filter(continent=="Africa") %>% glimpse # visualise just africa

# summarise data into one line  
gapminder %>% 
  summarise("MinYear" = min(year,na.rm = T),
            "MaxYear" = max(year),
            "CountryCount" = n_distinct(country),
            "Counts" = n()
            )

gapminder %>%  
  summarise(median(lifeExp))

# filter
require(gapminder)
gapminder %>% 
  filter(continent == "Africa") 

# group by 
gapminder %>%  
  group_by(continent) %>% 
  summarise(median(lifeExp))


# group by continent and filter by year
gapminder %>% 
  group_by("Continent" = continent) %>% 
  filter(year == 1992) %>% 
  summarise(LifeExpect = median(lifeExp)) -> life_cont_1992

# rename specific cols
df %>% 
  rename(.cols = 2:5, # only rename these cols
         "Country" = 2,
         "Gold" = 3,
         "Silver" = 4,
         "Bronze" = 5)

# replace case when values based on numeric range
df %>% 
  mutate(var1 = case_when(
      between(var2, 1, 5) ~ "A",
      between(var2, 6, 10) ~ "B",
      T ~ var1)
      )

Execute unfriendly pipe functions inline in pipes

require(palmerpenguins)
require(dplyr)
p <- penguins

# %T>%
p %T>% glimpse %>% select(island)

# with()
p %>% with(lm(body_mass_g ~ flipper_length_mm)) %>% summary()

# %$% when var on lhs is undefined
require(magrittr)
data.frame(z = rnorm(100)) %$% ts.plot(z)

Apply function easily using mutate_at

# eg 1
df %>% mutate_at("var1", ~str_replace_all(., " ", "<br>"))

# eg 2
df %>% mutate_at("layer", ~replace(., is.nan(.), 0))

Generic functions

Convert character class to numeric (ideal when creating colour palettes to turn string cols in df to numeric)

require(dplyr)
set.seed(12)
df <- data.frame(X = LETTERS[sample(20)])
int_vec <- df$X %>% unlist %>% as.factor %>% as.integer  # converts to numbers 
int_vec
df$I <- int_vec
df

Pipe vector to multiple arguments

require(dplyr)

# as list
Sys.time() %>% list(format(., c("%y-%m", "%Y-%m", "%Y-%m")))

# use curly braces to keep original class
Sys.time() %>% {
    format(., c("%y-%m", "%Y-%m", "%Y-%m"))
}

Merge/combine/match/fill rows of two data frames based on value and retain original number of rows

merge(a, b, by = "ID", sort = F)

Access vars in df/tibble that failed to load eg. time series that return NA

# as tibble
df %>% attr("problems")

Search available methods for package

showMethods("coerce", classes = "sf")
methods(st_as_sf)
`?`(methods)

Get object size

df %>% object.size()

Google drive

Access files on Google Drive
Common commands: find, ls, mv, cp, mkdir, rm
http://googledrive.tidyverse.org/

require(googledrive)
drive_find(n_max = 10)  # set output limits
drive_find(type = "folder")
drive_get("~/Data/eli/feb.csv")

HTML code

code <- "<!DOCTYPE html>
  <html>
<body>

<h1>My First Heading</h1>

<p>My first paragraph.</p>

</body>
</html>"

code <- paste(as.character(code), collapse = "\n")

write.table(code, file = "/Users/code.html", quote = FALSE, col.names = FALSE, row.names = FALSE)

Extracting multiple nodes/range of nodes at once

# require(dplyr,rvest,xml2,readr,magrittr)
url <- "https://www.postholer.com/databook/Appalachian-Trail/3"
url %>% read_html() %>% html_nodes("table") %>% .[1:3]  # get range (node)
url %>% read_html() %>% html_nodes("table") %>% .[[1]]  # get individual (nodeset)

Interactive plots

Clickme, NVD3, Polychart, rCharts, Rickshaw, and xCharts in R.
Link to collated Github page.

Leaflet

Interactive label options and custom tiles

require(leaflet)
require(dplyr)
require(geosphere)
require(htmltools)

setview <- c(7.369722, 12.354722)
mp <- data.frame(name = c("Melbourne", "Atlanta"), lat = c(-37.813629, 33.748997), lon = c(144.963058, 
    -84.387985))
latlon_matrix <- matrix(c(mp[, "lon"], mp[, "lat"]), ncol = 2)
custom_tile <- "http://a.sm.mapstack.stamen.com/(positron,(mapbox-water,$776699[hsl-color]),(buildings,$002bff[hsl-color]),(parks,$6abb9d[hsl-color]))/{z}/{x}/{y}.png"
colv <- "#4C3661"
opac <- 0.5
site_names <- mp$name
ttl <- "Debunking Flat Earth theory 101"
weblink <- "https://github.com/darwinanddavis"  # weblink
webname <- "My github"
href <- paste0("<b><a href=", weblink, ">", webname, "</a></b>")
text_label <- paste(sep = "<br/>", href, "606 5th Ave. S", "Seattle, WA 98138")
# label options
marker_label_opt <- labelOptions(textsize = "20px", opacity = 0.5, offset = c(0, 0))
text_label_opt <- labelOptions(noHide = T, direction = "top", textOnly = T, opacity = 1, offset = c(0, 
    0))

# title
tag.map.title <- tags$style(HTML(".leaflet-control.map-title { 
       transform: translate(-50%,20%);
       position: fixed !important;
       left: 50%;
       text-align: center;
       padding-left: 10px; 
       padding-right: 10px; 
       background: white; opacity: 0.7;
       font-weight: bold;
       font-size: 25px;
       }"))
title <- tags$div(tag.map.title, HTML(ttl))


# map
map <- gcIntermediate(latlon_matrix[1, ], latlon_matrix[2, ], n = 100, addStartEnd = T, sp = T) %>% leaflet() %>% 
    setView(setview[2], setview[1], zoom = 3) %>% addTiles(custom_tile) %>% addCircleMarkers(mp[, "lon"], 
    mp[, "lat"], radius = 10, stroke = TRUE, weight = 3, opacity = opac, color = colv, fillColor = colv, 
    label = paste(site_names), labelOptions = marker_label_opt) %>% addPolylines(color = colv, opacity = opac) %>% 
    addPopups(-122.327298, 47.597131, text_label, options = popupOptions(closeButton = FALSE, textOnly = T)) %>% 
    addLabelOnlyMarkers(setview[2], setview[1], label = text_label, labelOptions = text_label_opt) %>% 
    addControl("@darwinanddavis", position = "topright") %>% addControl(title, position = "topleft", 
    className = "map-title")
map

Lists

Transpose list (flip list elements)

l <- list(1:2, 3:4, 5:7, 8:10)
l
b <- data.table::transpose(l)
b

lengths for getting length of list indices

require(dplyr)
ls = list(rep(list(sample(50, replace = T)), 5))
ls %>% length
ls %>% lengths
lapply(ls, lengths)

Split list into smaller sublists

la = rep(list(1:5), 6)
names(la) = rep(LETTERS[1:3], 2)
u <- length(unique(names(la)))
n <- length(la)/u
split(la, rep(1:n, each = u))

# for when list has two elements in the name that change create a list of 10 letters with 5 lists in
# each
big_list <- rep(list(1:10), 5) %>% pmap(list)
names(big_list) <- LETTERS[1:10]
# to index the upper list
big_list["B"]  # 1
pluck(big_list, "B")  # 2
# to index the sublists
map(big_list["B"], 3)  # 1
bb_final <- list()  # 2
for (i in 1:10) {
    bb <- big_list["B"]
    bb_final <- c(bb_final, bb)
}
bb_final

Fill list elements with NAs to match length of longest element

# https://stackoverflow.com/questions/34570860/add-nas-to-make-all-list-elements-equal-length

# for single index list
set.seed(1)
ls = replicate(5, sample(1:100, 10), simplify = FALSE)
names(ls) = LETTERS[1:length(ls)]
lapply(ls, `length<-`, max(lengths(ls)))

# for sublists
ls = list(replicate(5, sample(1:100, 10), simplify = FALSE))
n.ticks = 20
fillvec = function(x) {
    nv = lapply(x, `length<-`, n.ticks)  # fill remaining vec with NAs to match total length
    rapply(nv, f = function(x) ifelse(is.na(x), 0, x), how = "replace")  # replace NAs with 0s
}
lapply(ls, fillvec)  # apply fillvec to list

Access list elements in loop by name/string

set.seed(12)

# inputs
time <- 5
time_vec <- 1:10
a_vec <- runif(10)
beta1_vec <- 1:10
beta2_vec <- 11:20
param_vec <- list(a_vec,beta1_vec,beta2_vec)
names(param_vec) <-c("alpha","beta1","beta2") 
params <- sapply(rep(NA,length(param_vec)),list) # create empty final params vector
names(params) <- names(param_vec)

# select parameter to test 
param_input <- "alpha" #beta1 #beta2

# run from here -----------------------------------------------------------
for(time in time_vec) {
  p_in = param_vec[`param_input`][[1]][time] # get parameter value by name
  # create new list of with updated param_input value
  params <- c(param_vec[-which(names(param_vec)==param_input)], # everything but param_input
              param_input = p_in # param_input
              )
  # get just the latest value
  # remove this if you want all list elements
  params <- sapply(params,function(x) x[1]) %>% as.numeric 
  # rename this new list
  names(params) <- c(names(param_vec)[-which(names(param_vec)==param_input)], # everything but param_input
                     param_input
                     )
  print(params)
} # end loop
params # each list element changes depending on user input 

Apply function to nested lists

ls = list(replicate(5, sample(1:100, 10), simplify = FALSE))
ls %>% glimpse
lapply(ls, lapply, mean)
lapply(ls, sapply, mean)  # return as one list 
rapply(ls, mean, how = "unlist")  # unlist, replace, or list

Apply function to list (without lapply)

require(lubridate)
ft <- c(now(), now() %>% rollback(), now() %>% rollback(roll_to_first = T))
ftl <- ft %>% list(isoyear(.), epiyear(.), wday(.), wday(., label = T), qday(.), week(.), semester(.), 
    am(.), pm(.))
names(ftl) <- c("data", "international standard date-time code (ISO 8601)", "epidemiological year", "weekday", 
    "weekday as label", "day into yearly quarter", "week of year", "semester", "AM?", "PM?")

Plotting

Hand drawn plotting using roughViz.js. Link to package page.

# install.packages('remotes') remotes::install_github('XiangyunHuang/roughviz')
require(roughviz)

Read in data

Read in csv data sources directly from web

# link to raw csv link on e.g. github
require(readr)
url <- "https://raw.githubusercontent.com/plotly/datasets/master/2011_february_aa_flight_paths.csv"
flights <- read_csv(url)

Regex

resource_type <- "algae"
# this regex expression
list.files(pattern = paste0("^", resource_type, "_[0,5]{1}_[0-9]{1,2}_hostpop50_predpop", "[0-9]{1,3}_rep[1-5]{1}\\.R$"))
# returns this begins with resource_type, either 0 or 5 as one integer, 0 to 9 as either one or two
# integers, 0 to 9 as one to three integers, and 1 to 5 as one integer
"algae_0_5_hostpop50_predpop5_rep1.R"
"algae_5_20_hostpop50_predpop30_rep2.R"
"algae_0_15_hostpop50_predpop150_rep5.R"

Rmarkdown

---

Split page into three columns (displays best in browser).
R code is in Rmd file.

# r plot code
require(ggplot2)
ggplot(mtcars, aes(x = mpg)) + geom_histogram(fill = "skyblue", alpha = 0.5) + theme_classic()

Praise the lord, I was born to travel
Feeling like Slash in front of the chapel
I'm leaned back with the Les Paul
Shit I smoke is like cholesterol
Spilled dressin' on the vest at the festival
The best of all, had a midget Puerto Rican at my beckon call

Pump the bass in the trunk
It rattled like a baby hand
Except this toy cost 80 grand
And I'm crazy tan, from all the places that I've been
Just from writing words with a pen

   

Inserting text within indented equations
\[ p(x) = \theta^{x} (1 - \theta)^{1-x} ~~\mbox{ for }~~x = 0,1 \]

Remove white space around imgs using fig.asp

plotly

HTML widget with plotly and crosstalk

require(pacman)
p_load(plotly,tidyr,crosstalk)

m <- gather(mpg, variable, value, -c(year,cyl)) # data source
msd <- highlight_key(m, ~variable) # var to highlight 
gg <- ggplot(m, aes(factor(year), value)) + # ggplot obj 
  geom_jitter(alpha = 0.3) +
  labs(x = "Year") +
  theme_classic()

# create layout 
bscols(
  widths = c(11, rep(5,2)), # max = 12
  filter_select("id", "Select a variable", msd, ~variable, multiple = F), # dropdown menu
  ggplotly(gg, dynamicTicks = "y") %>% 
    layout(margin = list(l = 30)),
  plot_ly(msd, x = ~jitter(cyl), y = ~value, alpha = ~cyl, linetype = NULL, 
          mode = "markers",
          hoverinfo = "text", 
          text = ~paste0("Cyl: ", round(cyl),
                        "\n",variable,": ", value,
                        "\nYear: ", year)
          ) %>% # interactive vars
    add_markers(alpha = 0.3) %>%
    layout(xaxis = list(showgrid = F, # general plot params 
                        title = "Cylinder"),
           yaxis = list(showgrid = F)
    )
)

Select a variable

# example 2 with changing output margins to fill browser 


require(htmltools)

# title
plotbg <- tags$html(
  HTML("<body style=\"background-color: black;\"></body>"))

resource_type <- "detritus"
memi_df <- readr::read_csv("https://raw.githubusercontent.com/darwinanddavis/mybio/master/data/memi_df.csv")
memi_df <- data.frame(memi_df)
memi_df %>% str

'data.frame':   3600 obs. of  7 variables:
 $ X1              : num  1 2 3 4 5 6 7 8 9 10 ...
 $ ME_EVENT        : chr  "skip30_0" "skip30_0" "skip30_0" "skip30_0" ...
 $ Cercs           : num  0 0 0 0 0 0 0 0 0 0 ...
 $ ControlImpact   : num  0 0 0 0 0 0 0 0 0 0 ...
 $ ControlDay      : num  1 1 1 1 1 1 1 1 1 1 ...
 $ ControlDay_names: chr  "Skip~30" "Skip~30" "Skip~30" "Skip~30" ...
 $ Time            : num  1 2 3 4 5 6 7 8 9 10 ...

# heatmap -----------------------------------------------------------------
require(viridis)
require(ggthemes)
require(plotly)

me_day_vec <- c("skip30","skip60","skip90","skip120")
me_day_names <- as.factor(c("Skip~30", "Skip~60", "Skip~90", "Skip120")) # char vec for labelling facets
ttl <- ""
subttl = ""
xlab <- "Time (days)"
ylab <- "Control intensity"
# turn names into function for labeller for facets
me_im_names <- c("No control","50%", "75%", "90%", "95%", "99%")
dens <- memi_df[,"Cercs"]
yy <- memi_df[,"ControlImpact"]
xx <- memi_df[,"Time"]
facet1 <- memi_df[,"ControlDay"]
p <- ggplot(memi_df,aes(x=xx,y=yy,fill=dens)) +
  geom_tile(colour= "gray",size=0.01, width=2, linetype = 0) +
  scale_fill_viridis(name="Density",option ="magma")
p <- p + facet_wrap(~ ControlDay_names,nrow=length(me_day_names), ncol=1, drop= F, labeller=label_parsed) # use for adding facet labels
# p <-p + facet_wrap(facet1, nrow=3, ncol=1, drop= F)
p <- p + scale_y_continuous(breaks = unique(yy), labels = me_im_names, trans = "reverse")
p <- p + scale_x_continuous(breaks = seq(0,max(xx),30), expand =c(0,2)) 
p <- p + geom_segment(aes(x = 152, xend = 152, y= 4, yend= 4),
                      arrow=arrow(length=unit(0.2,"cm")))
p <- p + theme_calc() + 
  theme(text = element_text(size=18)) +
  # labs(title= paste0("Density of ",ttl, " by ",subttl), y=ylab, x=xlab) +
  labs(title = paste0("\n","\n",ttl), y=ylab, x=xlab,size=3) +
  theme(plot.title = element_text(vjust=-7)) +
  theme(legend.position = "bottom",legend.direction = "horizontal") +
  theme(legend.text = element_text(size=12)) +
  theme(plot.background = element_rect(fill = "black")) +
  ggpubr::theme_transparent() 
  # plot_it_gg("black","white")

m <- list(
  t = 100,
  r = 1,
  b = 1,
  l = 1,
  padding = 4
)

p <- ggplotly(p)

require(htmlwidgets)
h <- p %>% 
  layout(
         plot_bgcolor = 'black',
         paper_bgcolor = 'black',
         font = list(color = 'black'),
         autosize = T, margin=m) %>% 
  sizingPolicy(padding = 0, browser.fill = TRUE,plotbg)

Crosstalk example 2

# time series plotly
pacman::p_load(dplyr, lubridate, ggplot2, plotly, gridExtra, plyr, ggthemes)
# install.packages('crosstalk')
library(crosstalk)

# load mock data
df <- readr::read_csv("/Users/malishev/Documents/Data/time_series/call_activity/call_activity.csv")
xinter <- seq(min(df$Date), max(df$Date), length.out = length(df$Date))

# plot data
p <- ggplot() + geom_vline(mapping = NULL, xintercept = xinter, colour = "grey80", size = 0.03) + geom_point(data = df, 
    aes(Date, Hour, color = Person, size = Calls)) + scale_y_continuous(limits = c(1, 23)) + scale_x_datetime(date_breaks = "1 week", 
    date_minor_breaks = "1 day", date_labels = "%D") + theme(axis.text.x = element_text(angle = 45)) + 
    labs(title = "Calls per hour of day", x = "Date (M/D/Y)", y = "Hour of day") + theme(panel.border = element_blank(), 
    panel.grid.major = element_line(color = "gray"), panel.grid.minor = element_line(color = "light gray"), 
    axis.line = element_line(color = "gray"))
p <- p + theme_hc()
ggplotly(p)

# plotly crosstalk
calls_person <- highlight_key(df, ~Hour)
person_person <- highlight_key(df)

pp <- bscols(widths = 12, p1 <- plot_ly(df, x = ~Date, y = ~Hour, color = ~Person, size = ~Calls, type = "scatter", 
    hoverinfo = "text", text = ~paste0("Date: ", Date, "\nName: ", Person, "\nCalls: ", Calls)) %>% layout(title = "Calls per hour of day", 
    xaxis = list(tickangle = 45, showgrid = T), yaxis = list(range = c(0, 23), showgrid = T), margin = list(l = 0.5)), 
    filter_select("id", "Select hour of day", calls_person, ~Hour, multiple = F), p2 <- plot_ly(calls_person, 
        x = ~Person, color = ~Person, type = "histogram") %>% layout(title = "Calls per person", yaxis = list(showgrid = F)))

pp <- htmltools::tagList(list(p1, p2))
`?`(`?`(tagList))

Sys.setenv(plotly_username = "malishev")
Sys.setenv(plotly_api_key = "uApW9Ar4GpjbEbagDeAn")

ff <- plotly::api_create(p1, username = "malishev")

subplot(p1, p2, nrows = 2)

htmltools::knit_print.shiny.tag.list(pp)

Gather/melt dfs to make dfs plotly friendly

require(tidyr)
require(plotly)
sm <- as.data.frame(EuStockMarkets) %>% gather(index, price) %>% mutate(time = rep(EuStockMarkets %>% 
    time(), 4))

sm %>% plot_ly(x = sm$time, y = sm$price, color = sm$index)

Strings

Detect strings in data frame or vector based on partial pattern. Useful when you don't know the complete name of data frame col.

df_names <- df %>% pull(var1) %>% unique
df %>% filter(var1 == df_names[str_detect(df_names, "va")])  # use partial string to pull df col

# dplyr version
iris %>% select(starts_with("Sepal"), contain("Sepal"), matches("Sepal"))

Time

Get just HMS portion of POSIX class

require(dplyr)
Sys.time() %>% format(format = "%H:%M:%S")

Convert character to hms format, esp for erraneous timedate data

pacman::p_load(lubridate, hms)

df %>% pull(var1) %>% as.factor %>% lubridate::hms() %>% period_to_seconds() %>% hms::as_hms()

Timezone converter

# get local tz
require(dplyr)
require(lubridate)
require(stringr)
itz <- "2021-02-01T02:22:59.000Z"
lubridate::ymd_hms(itz) %>% with_tz(OlsonNames()[OlsonNames() %>% str_which("Melb")])

Tables

Summary tables

remotes::install_github("ddsjoberg/gtsummary")
tbl_summary(
    trial2,
    by = trt, # split table by group
    missing = "no" # don't list missing data separately
  ) %>%
  add_n() %>% # add column with total number of non-missing observations
  add_p() %>% # test for a difference between groups
  modify_header(label = "**Variable**") %>% # update the column header
  bold_labels()